Heating system



March 12, 1940. BR WNE 2,193,160-

HEATING SYSTEM Filed Jan. 24, 1958 4 Sheets-Sheet 1 IN VEN TOR.

. A TTORNEYS.

March 12, 1940. BRQWNE 2,193,160

HEATING SYSTEM Filed Jan. 24, 1938 4 Sheets-Sheet 2 z x i nae/awn .flM/wed fi. Browne,

March 12, 1940.-

A. L. BROWNE HEATING SYSTEM Filed Jan. .24, 1958 4 Sheets-Sheet 3 IN V EN TOR.

W /6 ,40!- 90414: K ATTORNEYS.

March 12, 1940. BRQWNE 2,193,160

HEATING SYSTEM Filed Jan. 24, 193 4 Sheets-Sheet 4 Bolt 5/ IN VEN TOR.

fll/rm L BM /1e W, ,& -M1 ATTORNEYS.

Patented Mar. 12, 1940 UNITED STATES PATENT OFFICE HEATING SYSTEM Application January 24, 1938, Serial No. 186,551

19 Claims.

This invention relates to the art of steam heating. Its principal object pertains to the controlled circulation of steam to condensing surfaces over a wide range of absolute pressures,

below and above atmospheric pressure, with stress however, given to the controlled circulation of steam at pressures usually below atmospheric pressure.

The purpose of varying the absolute pressure and temperature of steam is to materially vary the heat emission from condensing surfaces so that said heat emission may approximately balance the heat loss of a space or structure for any given conditions.

Asa matter of prior art, it is fully recognized that there are many instances where steam has been circulated, purposely, or as natural phenomena, to condensing surfaces at sub-atmospheric pressures for at least or 30 years past. For instance, it has been common practice in many heating plants utilizing vacuum pumps to purposely retard the rate of boiler evaporation, either by banking fires or further throttling of pressure reducing valves to obtain a circulation of steam within condensing surfaces at subatmospheric or partial vacuum pressures.

On the other hand, as a matter of natural phenomena, where heating systems consist of low pressure boilers, piping connected from boilers to condensers (radiators) and thence from the radiator traps to an electrical driven vacuum pump, steam will frequently and naturally be circulated at sub-atmospheric pressure conditions within the boilers, piping, and radiators. In any closed heating system, whenever the evaporative rate of the boiler is less than the condensing rate of the radiators, boiler and radiator pressure will progressively drop to sub-atmospheric conditions, which will finally be limited by infiltration of air;

through leaks within the heating system, or, even by the provision of mechanical equipment to limit such a condition, as, for instance: the vacuurn breaking valve frequently employed as standard equipment on vacuum pumps for years. Such 5 pumps are usually supplied with a vacuum regulator set, say for illustration, to start the pump at '7" vacuum gauge and to stop the pump at 12'' of vacuum gauge. Therefore, when fires are banked and evaporation is reduced, or oil burners 50 are turned off, it is self-evident that under this established and usual condition that whenever the vacuum pump was not operating, steam would be circulated to the radiators; condensate and non-condensible gases extracted into the return line, without the loss of steam into the return line, up to 7" of vacuum gauge, (with an allowance for pressure drop within the particular system) and similar conditions would pertain up to 12" of vacuum gauge whenever the pump was operating.

Therefore, in an inexact and crude sort of way, it has been long a common occurrence to lower the steam pressure and temperature of steam in radiators to limited sub-atmospheric or vacuum pressure levels in common vacuum heating systems, in order to reduce the heat emission from radiators during ordinary winter weather.

My invention employs the combination of many ordinary and existing elements, common in standard vacuum heating systems -i. e. boilers, or other source of steam supply, piping, radiators, radiator supply valves, radiator return traps, re-

turn piping and vacuum pumpstogether with ordinary existing electro-mechanical devices, such as: thermostats, relays, aquastats, motorized valves, etc. In my new combination I employ an electrical switch, functionally responsive to a thermostat, as disclosed, for example, in my copending application Serial No. 14,203, filed April 2, 1935, and hereinafter designated as a selective controller.

In short, my new combinations represent refinements in vacuum heating that make possible the complete controlled circulation of steam within radiators over a broad range of absolute pressures, from 20 to 25 inches of vacuum gauge up to any selected pressures in pounds gauge above atmospheric pressure, usually associated with heating systems. This is accomplished by the utilization of the aforesaid "selective controller which at all sub-atmospheric radiator pressures, causes the vacuum pump to maintain a variable but materially lower pressure between the vacuum pump and the radiators, providing a pressure head, or difierential, between boiler, or steam source, and radiators, and radiators and vacuum pump. The practicable low boiler pressure obtainable in such systems does not ordinarily exceed approximately 24" vacuum gauge, as beyond this pressure level the power necessary to maintain a lower presure level at the vacuum pump becomes economically excessive.

Therefore, in some forms of my systems whenever the boiler pressure is lowered to the maximum low pressure level produced by the vacuum pump, say 24" or 25" vacuum gauge, the selective controller automatically causes the vacuum pump to stop operating. When, after a time, the 'general pressure level has risen within the entire system to a given pressure level, the selective controller restarts the vacuum pump;

In the accompanying drawings:

Figure 1 is an elevation, somewhat diagrammatic, showing the principal elements in system combinations in one form of my invention.

Fig. 2 is an enlarged detail elevation of a control assembly shown in Fig. 1.

Fig. 3 is an enlarged sectional detail view of a variable orifice or control metering valve shown in Fig. 2.

Fig. 3a is an enlarged inverted detail plan view of the plate 21 of the valve shown in Fig. 3.

Fig. 4 is a view similar to Fig. 1 but showing a modified form of my invention.

Fig. 5 is an enlarged sectionalized view of a preferred form of a pressure control trap shown in Fig. 4.

Fig. 6 is a sectionalized view of another form of pressure control trap shown in Fig. 5,.

Fig. '7 is an elevation of an alternate control of a motorized zone control valve shown in Fig. 4.

Fig. 8 is a view similar to Figs. 1 and 4 but showing a further modification of my invention.

Fig. 9 is a vertical section of the controlling device G shown in Figs. 1, 4 and 8.

Fig. 10 illustrates a modified form of certain structural details of the controlling device illustrated in Fig. 1.

Referring to Fig. 1: A indicates a boiler or other source of steam, supplying steam to radiators B through steam main I0, and risers. II, and radiator inlet valves K. Air, non-condensible gases and condensate are withdrawn through fluid thermostat radiator traps C, and conveyed through return risers l2, and return main l3, to vacuum pump E. Steam main l drips through drip trap D, preferably of the float and thermostatic type, into return main l3, and thence back to vacuum pump E. The vacuum pump E shown is of the electrical driven type, consisting of a motor, vacuum pump, condensate pump and receiving tank.

The pump unit E is equipped with a customary vacuum regulator switch F and a float control switch (not shown) within the tank. These controls operate independently of each other to return condensate through pipe M to the boiler, or to produce a given vacuum according to the setting of the vacuum regulating switch F. The type of vacuum pump illustrated has been in common use for many years past.

The selective controller G disclosed in my copending patent application Serial No. 14,203, is connected to the return line l3 near or preferably close to the vacuum pump E, in order that its thermostat shallbe responsive to the temperature and pressure conditions in the return line and near the vacuum pump. The electrical switch in the upper part of the selective controller G is responsive in action to the aforesaid thermostat. Wires II from the selective controller switch connect to the coil of a relay I 8. When the switch of selective controller G is closed, the relay I8 is energized and through its contacts, closes the electrical circuit through wires 19 to the vacuum regulator F. Then, if the vacuum regulator switch F (in series with the relay contacts) is closed, the pump will. operate. When the switch of the selective controller G is open, then the contacts of the relay l8 will remain open, preventing the operation of the vacuum pump in response to closure of the vacuum regulatorswitch F.

From the above, it will be seen that in this arrangement there are two electrical switch controls for the vacuum pump E. One, the standard vacuum control F which is a fixed pressure control having a fixed pressure range or differential, in response to which the motor of the vacuum pump E starts and stops. The second control, the selective controller G, which is wired to the relay whose contacts are in series with the standard vacuum controller F, is a floating control which, in response to a change in temperature, or a change in pressure, or a combination of a change in pressure and temperature in the return line l3, will conditionally assume control and become the master control of the vacuum pump operation, starting and stopping the motor of the vacuum pump E, at pressure levels that fluctuate with temperature-pressure conditions in the return line l3, when the standard vacuum regulator F is in a closed position and which ordinarily, acting as a limit switch, would cause the vacuum pump E to run.

On the control instrument panel H, there is mounted the aforesaid relay l8 and another like relay 20. This relay 20 is electrically wired to an aquastat 2|. The aquastat 2| is connected in back of the panel H and extends into a suitable well (not shown) in a steam line It from the steam main. Steam line I6, after connecting to the aquastat 2|, is suitably dripped through a fiuid thermostatic trap C, discharging into a return pipe H, which connects to a.- steam circulation balancer l (see also Fig. 2). The lower part of the circulation balancer I5 is constructed as a liquid seal of some depth, through which condensate from the steam supply pipe l6 can freely pass into the return line B, then into the receiving tank of vacuum pump E. At the upper portion of the steam circulating balancer l5 (Fig. 2) there is an adjustable metering control valve I shown also in Fig. 3. This valve I acts as a choke and in its preferred form consists of a fixed lower plate 28, in spring loaded contact with a rotating upper plate 21. The lower plate 28 has one relatively large orifice through it and the upper plate 21 has a series of progressively smaller orifices through it. In manually setting this valve, the upper disc 2'! is partly rotated until the desired orifice registers in vertical alignment with the larger single orifice in the lower fixed plate 28. Thus, various degrees of restriction can be made, affecting the circulation of steam through pipe [6, to the aquastat 2|.

The aquastat is preferably one having a range of adjustment to cause its contacts to close at any desired temperature between 100 F. and 240 F. According to the temperature setting, the aquastat acts, through electrical connections 24, to operate the relay 20. The usual pressure controller 26 is connected in series with the contacts of the relay 20 in the circuit 25. The pressure regulator 26 acts as a high pressure limit switch controlling the blower J or other automatic combustion unit. The aquastat 2|, when set at a temperature, whose corresponding steam pressure is less than the steam pressure that the high limit pressure control 26 is set for, acts to make and break the electrical circuit to the device J. Compound low pressure gauges 22 and 23 mounted on the control panel H, are connected in the usual manner to the supply and return piping, and provide an indication of the steam pressure and return line pressure.

In this particular aforesaid arrangement illustrated in Figs. 1 to 3, the aquastat 2| constitutes the control means of steam pressure level within the heating system, for instance: if the aquastat indicator is set at 176 F. on its scale, this causes the blower J (which may be a blower used in connection with small grades of solid fuel such as #2 Buckwheat anthracite) to function whenever the temperature within the boiler A is something less than 1'76 F. and to cease functioning when the temperature within the boiler A is something above l76 F. This would correspond to a pressure level expressed as 16" of vacuum gauge. Assuming that the radiator traps C of the radiators B are in good operating condition, the temperature in the return line I3 at the selective controller G, near the vacuum pump E, would then likely be in the neighborhood of 102 F. Under the usual setting of my selective controller G, described in my cited co-pending application Serial No. 14,203, this selective controller G would then open the circuit to the vacuum pump E. The usual setting of the selective controller G, is such that it will open the circuit of the vacuum pump E at a temperature that is approximately 50 F.

,lower than the pure steam temperature for a given pressure in the return line. Therefore, the pressure for 152 F. would be 22" of vacuum gauge.

There thus being 22" of vacuum at the vacuum pump E, and 16" of vacuum in the boiler A, there is ample pressure head, or difierential, between the two sides of the system to effect a complete circulation of steam from the boiler A through the steam main l0, steam risers Hand into and completely filling the radiators B. The radiator traps C, and drip traps D permit the escape of condensate, air and non-condensible gases into return line l3.

The temperature in the return line l3, being a function of the temperature of the steam within the boiler A, does not tend to vary very much unless there is a change in the temperaturepressure level within the boiler A. Assuming that the temperature-pressure level in the boiler A is held approximately constant by the aquastat 2|, then, after a time, the pressure within the return line l3 rises with little, if any, change in the temperature within the return line 3 at the selective controller G. Therefore, assume that the pressure level has risen to a point that corresponds to 18" of vacuum gauge, then, the selective controller G re-starts the vacuum pump E, causing the same to operate until the pressure is again lowered to 22" of vacuum, as previously described. These conditions would pertain indefinitely so long as the boiler pressure level was maintained constant.

Assume that the aquastat 2| is set to cause a higher pressure-temperature level, then, the consequent rise in temperature in the return line l3 causes the selective controller G to break the electrical circuit to the vacuum pump E until the pressure level within the return line l3 has risen to some higher level. This level would bear about the same relationship as previously described, where the boiler pressure was 16" of vacuum and the open circuit pressure temperature level of the selective controller G was 2 of vacuum. If the aquastat 2| was advanced so that a temperature pressure level of 5" of vacuum was maintained in the boiler A, then, the open circuit pressure-temperature level at the selective controller G would be approximately 11" of vacuum. I

Conversely, if the aquastat 2| was retarded to a temperature-pressure level of 133 F. (25" of vacuum gauge), then the selective controller G would operate to hold the electrical circuit to the vacuum pump E closed. However, the vacuum regulator F, would then operate as a low limit pressure control switch. Assume that it was set to open the circuit of the vacuum pump E at 25" of vacuum gauge and to close the circuit at 22" of vacuum gauge. Then the control of the vacuum pump E would automatically be transferred to the standard vacuum regulator F, which, as stated, is purely a fixed pressure differential electrical switch.

If the aquastat 2| is now set to operate the blower J at a temperature-pressure level lower than 25" of vacuum, the blower J will cease to operate. The pressure in the boiler A and at the vacuum pump E, being approximately 25" of vacuum, there would not exist any pressure head or difierential effecting a positive circulation of steam to the radiators B. Therefore, the

radiators B gradually cool off and the pressure level within the entire heating system gradually rises. After a period of time; for illustration: 30 minutes to an hour, this pressure level within the entire system would rise to the cut-in pressure level of the vacuum regulator F, namely: 22" of vacuum. In the meantime, there would be a heat gain in the water in the boiler A due to the continued combustion of coal even though the blower J was not operating in response to the described setting of the aquastat 2|. This heat gain would correspond in temperature to the temperature pressure level of the heating system, namely: 22 of vacuum, approximately 152 F. The vacuum pump E starts at this pressure level of 22" of vacuum, and quickly acts to drop the pressure level to 25" of vacuum. In so doing, this lowered pressure would be conveyed back to the return line l3, return risers l2 and through the radiator traps C and radiators B;

thence through risers ll, into the steam main |0 and thence into boiler A.

This sudden lowering of the pressure within the boiler A, converts the excess sensible heat for the given pressure level into latent heatof evaporation from 152 F. down to 133 F. The steam so generated acts as a shot supply of steam to the radiators B. On a mild day, if the aquastat 2| is left at this particularly described setting of 25", or is ofi, shots of steam will be supplied to the radiators B periodically, with interspersed cooling of the radiators B, thus providing a mean temperature level within the radiators B, and a consequent heat emission from the radiators B, over a period of time far less than would be obtained by maintaining any con tinuous supply of steam to the radiators at any possible practical pressure temperature level.

Continuous supply. of steam (as contrasted with the periodic shot supply, just described) at the pressure-temperature level of approximately 133 F., at approximately 25" of vacuum, would provide more heat than required during mild days. This particular minimum pressuretemperature level, with continuous supply of steam, would tend to overheat a structure whose heating system was designed on the basis of 70 F. temperature, 1 lb. pressure, zero outside weather, whenever the outside weather was in excess of approximately F.

The purpose of the circulation balancer I5, Fig. 2, is to provide a more accurate and better control of the periodicshots of steam to the radiators B, whenever the aquastat 2| is off or is set at a lower level than 133 F. and 25" vacuum." I I, I

The steam line It, into which the well of the aquastat 2| extends, connects with the return line l3, through the circulation balancer i5, Fig. 2. In efi'ect, the pipe IS with its trap C constitutes a radiator, exactly the same as the usual radiators B, and operates likewise.

The purpose of the circulation balancer I5 is to simply act as a choke. This is accomplished by rotating the valve I, Fig. 3, until a sufllciently small orifice in the upper rotating plate 2'! is in alinement with larger orifice of the lower fixed plate 28. When properly balanced this synchronizes the cooling and heating action of the aquastat 2| in step with the cooling and heating action of the more remote radiators B. To illustrate: if the blower J is not operating and the vacuum pump E is not operating and the general pressure within the entire heating system-is uniform, the radiators B will tend to cool due to the lack of any pressure head. This cooling action normally occurs by air and non-condensible gases re-entering the radiators B through the traps C, occupying space within the radiators B previously occupied by steam. Precisely the same action occurs in the control line l6. Air and other non-condensible gases are drawn back through the radiator trap C,'and occupy space within control line l6, previously occupied by steam.

Valve I, Fig. 3, set as previously described, tends to retard the flow of these gases back into the control line IB. With the proper orifice in the valve I selected, the temperature conditions in the thermostatic well of the aquastat 21, in the return line I6, would be approximately the same temperature as that within the radiators B. This temperature might be, for example: 100 F. in the steam line H5, at the aquastat 2| well, and substantially the same in radiators B, The temperature, however, of the water in the boiler A would correspond to the pressure level imposed upon it. Inasmuch as that pressure level ordinarily would not be lower than 25" of vacuum, the temperature would not be lower than'v 133 F. At this point, the aquastat M, if set to operate at 100 F., would function to start the blower J. This generates steam and raises the pressure level. However, the selection of the proper orifice in the choke valve I prevents the circulation of steam from occurring too quickly through the control line It, until .sufficient steam is generated to provide a circulation of steam to the furthermost radiators B.

It should be borne in mind that simultaneously the pressure level soon reaches a point, namely: 22" of vacuum, where it starts the vacuum pump E. Therefore, there is at the same time a lowering of the pressure with the'return side l3 of the system and a rise in pressure within the supply side ID of the system. This progressive increase in differential quickly provides the radiators B with a shot of steam and simultaneously accelerates the exit of cool gases through the choke valve I, causing also a quick rise in temperature in the aquastat well, causing the aquastat 2| to stop the operation of the blower J.

In view of the foregoing disclosure, it will be understood that in this particular system illustrated in Figs. 1 to 3, a continuous supply of steam may be maintained at definite pressure levels within the radiators and at the boiler A, and that automatically, lower definite pressure levels may be maintained in the return line and at the vacuum pump E, at all desired times, whenever the outside weather conditions require a constant supply of steam to the radiators B.

Also, particularly by the use of the circulation balancer l5 previously described, intermittent shots of steam may be eflectively provided to the radiators with interspersed periods when steam is not provided to the radiators, whenever the outside weather conditions are such that a continuous supply of steam even at the lowest pressure-temperature level obtainable would tend to over-heat the building.

Fig. 4 illustrates a modification of the system shown in Fig. 1. However, in this particular system, the pressure within boiler A is main tained at some constant level, usually above atmospheric pressure, for example, 2 lbs. gauge. This pressure would prevail within the boiler A and its steam main 10, which latter may be a steam header. Steam supply pipes II connect into motorized valves N. Each motorized valve N connects into a zone system of piping shown as zone L and zone M. Pipe connections I6A and i 6B, zone L and zone M, extend from the low pressure side of the motorized valves N to the aquastats 2IA, 2IB respectively, thence they are dripped through the traps C into the return line I3. Steam is supplied to the radiators B through valve K, and air and non-condensible gases pass out of the radiators B through the traps C into the return risers l2 and thence into pressure control traps 0 (one for each zone) and thence from the pressure control trap 0 from each zone into the general return line I3, which, in turn, connectsto the vacuum pump E. Condensate is discharged from vacuum pump E through the pipe l4, back into the boiler A. The characteristic circulation of steam within this system described in Fig. 4 is essentially the same as that described in Fig. 1, with the exception that different pressure may be imposed through the motorized valves to different sections or zones of the system.

The motorized valves N may be of any standard pneumatic or electric type in common use. However, it is preferable to use an integrating type of motorized valve, providing a fioating control action rather than the definite off and on action. The motors of the motorized valves N are connected through wiring connections 25 to the aquastats ZIA and 2IB respectively, and are controlled by their respective aquastats to maintain given respective pressure levels in zone L and zone M according to their settings. For instance: the aquastat 21A of zone L may be set so to operate the motorized valve N that the steam pressure within zone L and its radiators B would be of vacuum, 161 F., while the aquastat 21B, zone M may be set so to operate the motorized valve N that the steam pressure within zone M and its radiators B would be 1 lb. gauge, 215 F.

Obviously, the discharge temperature of the condensate from radiators B in their respective zones L and M, under the conditions cited Would vary greatly. In zone L, customary radiator traps under this 20" vacuum level would be discharging condensate at approximately 141 F. while radiator trap C connected to the radiators B, in zone M, would be discharging condensate at a temperature of 195 F.

Inasmuch as the operation of the vacuum pump E, in response to control by the selective controller G, or the standard vacuum regulator control F, as previously described in connection with Fig. 1, would necessitate operating the vacuum did pump E to maintain a pressure level materially less than 20" of vacuum to insure complete circulation of steam to and through all radiators in zone L, it is self-evident that the much hotter condensate from the radiator trap C in zone M, together with the increased leakage through these radiator traps due to the wide differential, namely: 1 lb. to approximately 25" of vacuum, would impose a burden upon the vacuum pump under the conditions cited that would require excessive power to maintain the required low pressure level.

Pressure control traps O are interposed between return risers M which extend from the respective zones L and M, to the common return main 13. The function of the pressure control traps is to decrease this pressure diiierential across the radiator trap valve members, particularly in the zone having the highest steam pressure and thereby minimize leaking of steam through the radiator traps and to provide some cooling of the condensate discharge from the zones operating at higher steam pressure levels and thus minimize the load imposed upon the vacuum pump E.

Fig. 5 and Fig. (3 illustrate two types of pres-= sure control traps O. In Fig. 5 the trap is a combination float and thermostatic trap, while in Fig. 6 the pressure control trap is purely thermostatic in action.

Fig. 5 shows the preferred form of trap. Condensate flowing through the return riser it into the left hand side of pressure control trap G cools somewhat due to the storage effect of condensate within the trap, and the decreased velocity of condensate through it. However, the principal advantage of the trap is due to the action of the thermostat 29. The operation of this thermostat 29! generally corresponds to the operation of the thermostat controlling the switch mechanism in my selective controller G, and so functions that whenever the temperature surrounding it is approximately 30 F. less than the pure steam temperature for any given pressure level, it causes the valve member 30 to close. Under the conditions cited in zone M, this would be a temperature of approximately 195 F. or approximately 8" of vacuum. Therefore, the pressure level between trap 0, zone M and radiator traps C would be 8" of vacuum gauge; the pressure level within the radiators B, as stated, being 1 lb. This differential is not excessive and minimizes steam leakage through the trap C, due to this reduction in the total differential at the vacuum pump E being imposed upon trap C in zone M. If, for instance, the vacuum in the pump happened to be 25" gauge, this pressure level would extend only to discharge pipe connection l2 of the control trap 0 connected to zone M.

. Between the low pressure side of the motorized from the outlet return line connection I! and from control trap O to the vacuum pump E.

Referring again to zone L, previously described as operating at 20" of vacuum steam pressure, the thermostat 29 would be sufficiently contracted to permit the valve member 30 to remain partially open, and the pressure of 25" of vacuum in the return line l3 would be conveyed through said trap O and into the return line system I! of zone M up to radiator traps, because the temperature diiferential between the steam being supplied to the radiators, namely 161 F. and the corresponding pure steam temperature level for the pressure of 25" of vacuum at the vacuum pump E and the return line i3 is less than 30 lower than temperature of steam being supplied to radiators B, zone L.

Therefore, from the above it will be apparent that wherever, in a zone or zones, the temperature level in the respective returns is excessively high in relationship to the temperature level in other returns, the pressure control trap O automatically functions, as described, to reduce the loading of the vacuum pump and to provide conditions favorable for the vacuum pump E to attain the highest vacuum possible. An additional control trap 0 may be employed at the end of the steam main in between the drip trap D and the main return it, and to function automatically to create three pressures between the steam main it and return main I13, as described above with respect to zone L and zone 'Vl.

Mounted on the instrument panel H, the relays 2t function in connection with the aquastats 2 IA and MB, to operate the motors of the motorized valve N. These may or may not be required according to the characteristics of the motors employed in connection with the motorized valves N.

Steam compound gauges 22 and steam compound gauges 23 indicate respectively the steam pressures of each zone, and the return pressures of each zone.

Fig. '7 indicates the use of a thermostatic control method of operating the motorized valves N, whereby the thermostat M is located in a space to be heated by a zone, with wired connections 32 to the motorized valve N. This thermostat 30 may be employed directly to maintain an interior temperature level, or may be employed in connection with an exterior type of thermostat.

In a system where room-temperature-level thermostatic means are employed, such as indicated in Fig. 7, the aquastat control responsive to steam temperature level, namelyv the aquastats 2 HA and MB, together with their wiring connections to the zone control valves N, and their piping connections 16A and NB, would be omitted.

In Fig. 8, there is illustrated another variation of my invention in which the vacuum pump E is of the well-known air line type instead of the equally well-known return line type shown in Figs. 1 and 4. In all respects this Fig. 8 system operates similar to the system illustrated in Fig. 1, with the following exceptions:

(1) Instead of an aquastat controlling definite steam pressure levels, a thermostat Si is employed through suitable electrical wiring 25, to control the blower J, thus automatically maintaining the proper steam pressure level in the boiler A, according to the room temperature level requirements of the building to be heated.

(2) The vacuum pump E (Fig. 8) is of the wellknown air line type instead of the well-known return line type indicated in Fig. 1 and Fig. 4. This pump (Fig. 8) operates only to expel air and other non-condensible gases from the system.

(3) In heating systems, particularly small heating systems where the returns l3 are horizontally elevated above the water line of the boiled A, a distance of approximately 30" or more, a boiler return trap 33 (Fig. 8) may be satisfactorily employed to return condensate to the boiler. This trap 33 has the usual equalizing steam connection 31 and vent connection 38 as shown. There is further employed a non-return air venting trap 34 as indicated. Such traps are well known. However, more specific detailed information referring to the functional characteristics of the boiler return trap and the air venting traps as I here employ them in this invention may be obtained by referring to my United States Letters Patent No. 1,772,239.- The air venting trap 34 will act only to permit the expelling of air and other non-condensible gases from the heating system when the system is operating materially above atmospheric pressure, with or without the use of the air line vacuum pump E.

(4) An aquastat 35, located m the steam main I0 near the boiler A is employed to open the circuit of the vacuum pump E whenever the temperature within the steam main at or near the boiler A is so low that it would indicate that the fuel had been burned out. For instance: if the temperature level was room temperature level of 70 to F. undoubtedly there would be no combustion of fuel in the boiler A. Therefore, the aquastat 35, if set for this temperature level would prevent the useless operation of the vacuum pump E when no primary heat was being supplied to the boiler A.

(5) It will be noted that in Fig. 8 the standard vacuum regulator F indicated in Figs. 1 and 4, is dispensed with in connection with this particular arrangement. The selective controller G contains internal arrangement for adjustment so it may be set to open the electrical circuit of the coil of the relay It (whose contacts are in the motor circuit of the vacuum pump) at a pressure temperature level within the capacity of the vacuum pump and at temperature levels to be expected, for instance: if the vacuum pump had .sufiicient capacity to produce 26" of vacuum gauge when the boiler fires were banked and insumcient steam was being circulated to completely fill the system from the boiler at this pressure, then the selective controller G could be so adjusted or designed that it could open the circuit at 25" of vacuum at 70 F. Inasmuch as the temperature within the boiler room and the piping therein would not be apt to be below 70 F., then it is evident that the selective controller G can be employed as a limit control of the vacuum pump operation, as well as a floating control at higher levels of pressure when higher levels of pressure are carried in the boiler A and radiators B.

This particular arrangement of a system as illustrated in Fig. 8, broadly speaking, has the functional characteristics of the system illustrated in Fig. 1, inasmuch as a continuous supply of steam is maintained to and through all radiators at various pressure levels with the exception that the combustion in the boiler A is retarded by the action of the thermostat III, so that the pressure level within the boiler A and radiators B drops to the level of the pressure range of the vacuum pump E under the control of the selective controller G. For illustration: assume a low limit vacuum range from 22 of vacuum to 25" of vacuum. Then the radiators B would be provided with shots of steam as fully described in connection with the system arrangement in Fig. 1.

In the foregoing descriptions I have disclosed the arrangements of my systems when a typical standard blower J is employed. However, it is to be understood that the invention may be applied to any standard type of combustion, such as an oil burner or a coal burning boiler employing customary drafts. Where a damper regulator is employed to control combustion, the thermostat 3| in Fig. 8, or the aquastat ill in Fig. 1, would operate to control a standard draft motor, which, in turn, would control the boiler drafts.

This application is a continuation in part of my application Serial No. 14,203, filed April 2, 1935, for Thermostatic control devices.

As stated, a suitable type of selective controller, designated G herein, is disclosed in my cited copending United States application Serial No. 14,203, filed April 2, 1935. The pressure-responsive thermostat there disclosed is so constructed and adjusted that it will cause its switch to open when the temperature in the return line rises sumciently to be within a substantially constant number of degrees lower than the pure steam pressure existing in the return line. Stated in another way, if a curve were plotted between inches of vacuum (between 25" and 0" of vacuum as abscissa) and corresponding pure steam temperatures corresponding to such degrees of vacuum (as ordinates) and another curve were plotted with the same abscissa but with ordinates corresponding to the temperatures at which the pressure-responsive thermostat (of the selective controller G) opens its switch, when subjected to thevarious inches of vacuum, the two curves would be spaced apart and substantially parallel to each other throughout their length between the limits 0" and 25" of vacuum, and would not cross each other between those limits. The vertical distance between those two curves, i. e. the substantially constant number of degrees" mentioned above, may be selected as desired by the construction and adjustment of the pressure-responsive thermostat. In my cited prior application Serial No. 14,203, the substantially constant number of degrees was disclosed as 30 F. In the instant application, the substantially constant number of degrees may be 30 F. in some instances, 50 F. in others, etc., depending upon the particular conditions and responsiveness desired. The desired result is attained by the particular volatile fluid employed within the pressure-responsive thermostat and by the degree of vacuum to which the interior thereof is subjected. I have attained satisfactory results by evacuating the interior of the pressure-responsive thermostat as completely as possible and then charging it with and sealing within it a suitable volatile fluid to attain the desired relationship above described.

I shall now describe the controller G in greater detail as it is described in my prior application Serial No. 14,203, reference being made to Figs. 9 and 10 of the present application.

The controlling device shown in detail in Fig. 9 is provided with a base plug I20 having a threaded boss I2I forengagement within a fitting in the return line. Base I20 carries a member I22, which in turn carries a member I23, which together provide enclosed chambers in communication with the interior of the return line of the heating system.

The base I20 carries an expansible member or bellows I24 which is contained in the chamber formed by member I22. The interior of the bellows is in open communication with the chamber I25 which is likewise supported by the base I20. The wall of chamber I25 extends within the interior of the return line so as to be subject to the temperature prevailing within the return line.

The contents of bellows I24 and chamber I25 are hermetically sealed therein from the space outside. Any change in volume of the contents results in an expansion or contraction of the bellows and a resulting movement of a rod I26 which is utilized for controlling the opening and closing of a circuit for efiecting the operation of a vacuum pump such as is used in a vacuum steam heating system, for example.

The chambers enclosed by members I22 and I23 are in direct communication with each other through an opening I2I through which rod, I 26 extends, and the two members are sealed in respect to the outside of the controlling device by suitable gaskets, so as to assure maintenance of pressure conditions within the two chambers the same as the pressure conditions within the return line of a heating system into which the wall of chamber I25 extends. The conductors I28, I29, are led from the interior of member I23 through a plug I30 of non-conducting material which is firmly held in place by a follower I3I.

Base I20 is provided with a passage I33 whereby pressure within the return line may be communicated to the interior of members I22 and I23 so that this pressure will be effective upon the outside of bellows I24.

It will be understood that there is no actual continuous fiow of gases through the chambers of members I22 and I23 and that the flow is confined to the equalization of pressures through the communicating ports only at such times as a change of pressure is occurring in the return line. These gases will be at a relatively high humidity. The wall surface of chamber I22 will condense some water from the gases, permitting a lower relative humidity of the gases in chamber I23. The ports are designed to permit equalization of pressure and at the same time to prevent active circulation of gases in these chambers. Ports I36 and III'I act simply as sealed over-flows, permitting any gradually accumulating moisture to return through the U seals at their lower ends back into the return line.

Member I23 houses the switch which is opened and closed, depending upon the position of the actuating rod I26, as controlled by the bellows I24. It will be appreciated that the choice of a switch is largely a matter of utilizing a contacting device which will respond satisfactorily for the purposes desired. I have obtained satisfactory results from the type of mercury switch illustrated, in which one of the conductors I28 has permanent connection with mercury I38 contained in a capsule I39, and the other conductor I29 is connected with one end of a spring I40 which has a movable end I4I capable of making direct contact with the mercury to close the circuit. The lower end of the spring is adapted to be attracted by a permanent magnet I42 carried by an arm I43 pivoted at I44. The magnet is effective only when the position of arm I43 is such that the magnetic field of the permanent magnet will be close enough to attract the free end of spring I40 (as shown in Fig. 9) against the natural tendency of the spring to maintain contacts I38I4I open. A standard I45 carries limit pins for limiting the movement of arm I43.

A weight I4] is attached to an arm I48, which is rigidly connected to arm I43, and this weight serves the purpose of urging arm I43 and magnet I42 into such position as will cause attraction of the free end of spring I40 and the closing of contacts I38--I4I, as illustrated in Fig. 9. .Arm I48 is normally supported by means of a strut member I49, which is likewise pivoted at I44. The lower end of member I49 is adapted to rest upon an arm I50 pivoted at I5I andthe outer end of arm I50 is bifurcated and extends on opposite sides of actuating rod I26 so that the member I49 may be lifted as the arm bears upon the upper side of nuts I52 carried by the actuating rod. The position of nuts I52 on the actuating rod determines when arm I43 will be rocked and contacts I 38I4I will be opened by expanding movement of bellows I24. When the bellows contract suiiiciently the weight I49, either alone or assisted by the upper set of nuts I53, will move the magnet I42 toward the free end of spring I40 and cause closing of contacts I38--I4I. The character of the contents of the chamber I25 and bellows I24 is similar to the character of the contents of commonly used bellows which contain volatile fluid and by which traps are thermostatically controlled in heating systems. The volatile fluid is indicated at I54, Fig. 9.

For a specific illustration a vacuum system of steam heating may be assumed with a vacuum pump regulator adjusted to cause the vacuum pump to operate between 9 and 14" of vacuum, as determined by gauge, having respective saturated steam temperatures of approximately 194 F. and 182 F. Under control of the regulator the vacuum pump would attempt to cut in and cut out at these limits of vacuum, regardless of the temperature of the condensate and gases in the return line.

With the steam pressure within the radiators sufilciently low and sufficiently close to the pressure range corresponding to 194 F. and 182 F., the temperature of the condensate and gases in the return line may be assumed as being in the neighborhood of 130 F. to 120 F., which are much lower temperatures than the temperatures corresponding to saturated steam temperatures for 9" and 14" of vacuum; and if the pressure in the radiators is now increased to 5 lbs. gauge with a temperature of 227 F., and it be assumed that the radiator traps would permit flow of condensate into the return line having temperatures ranging from say 200 F. to 210 F., the temperature in the return line would increase and upon reaching say 157 F. the controlling device of the present invention would break the circuit to the vacuum pump regulator and cause discontinuance of the operation of the vacuum pump. This temperature is within approximately 30 of the temperature of pure saturated steam at 12" of vacuum which is about 187 F.

After a time the temperature within the return line and at the vacuum pump would fall,

due to the fact that the pump was no longer operating to provide circulation, and after the temperature had fallen a predetermined number of degrees, say, for example, 5, the switch which had been open would automatically reestablish the circuit, permitting the vacuum pump to restart and operate in response to its regulator which would keep the vacuum pump operating until it had increased the vacuum to 14", or until leakage of steam or hot condensate afiecting the controlling device again caused the controlling device to discontinue the operation of the vacuum pump.

The controlling of the operation of the vacuum pump by my controlling device in the manner just referred to would continue so long as the steam pressures in the radiator were such as to create the conditions which cause my controlling device to take the cut out control or high vacuum limit control of the vacuum pump away from the vacuum pump regulator. On the other hand, when the steam pressure and temperature within the radiator drops sufiiciently, the vacuum pump would continue normal operation until it had increased the vacuum in the heating system to 14", at which point the standard regulator would automatically discontinue further operation of the vacuum pump. The

vacuum limits of 9" and 14" which I have referredto are given only to illustrate the application of my invention for attaining desired results at a selected range of pressures, and it is to be understood that the ranges may be varied to suit the operating conditions desired and the equipment making up any particular heating system.

It is to be understood that as the control effected by the thermostatic bellows of this device may be so regulated and set that it will cause the electrical circuit to break when the temperature in the return line rises sufliciently to be within a substantially constant number of degrees lower than the pure steam temperature for the pressure existing in the return line, it will cause the vacuum pump to cease operating even though the ordinary vacuum regulator is in the position of a closed circuit calling tor the operation of the vacuum pump.

My object is to control the operation of the vacuum pump to cause the vacuum pump to cease operating when the temperature in the return line reaches a point at which the vacuum pump would fail to reach the degree of vacuum that 1 its regulator was set for and would continue to operate without utility because of the presence of steam at the pump if no provision were made to discontinue its operation, or when the temperature in the return had reached a point when further operation of the vacuum pump would be without utility.

It is to be understood that in pumps of sumcient capacity and correct characteristics, the values which I have referred to by Way of example, i. e., vacuum limits of 9" and 14" may be to of vacuum at the vacuum pump, further increasing the effective temperature and pressure range of steam utilized within the radiators.

In Fig. 10 I have shown modified details of construction for providing a seal between chambers I22 and I23, and yet permitting for transfer of the actuating rod movement to the switch mechanism for such a case as where it is necessary or desirable to prevent damaging the switch mechanism by moisture or the corrosive effect of gases. The expansible diaphragm I58 seals out all communication of fluid flow between the chamber containing bellows I59 and the chamber containing the switch and mechanism I60 for operating the switch. The expansible diaphragm I58 may be a metallic cup shaped member having circular grooves in its side wall for permitting ready expansion and contraction of the diaphragm and consequent displacement of its end wall. The edge of the diaphragm is hermetically sealed to the partitioning wall IBI so as to prevent flow of fluid and equalization of pressures on opposite sides of the partitioning wall. Rod I62 has its lower end pivotaliy connected to the upper element of bellows I59 and its upper end attached to the inside of diaphragm I58. Rod I 63 is attached to the outer side of diaphragm I58 and the two rods act as one rod for actuating the switch operating mechanism I60,

The pressure conditions within the chamber enclosing the switch would be constantly atmospheric pressure. In the construction of Fig. 10 it is desirable to maintain as small a cross sectional area or diameter of the expansible diaphragm I58 as possible so as to minimize the downward thrust caused by atmospheric pressure exerted over the area of the expansible diaphragm. This arrangement would further require modification of the character of the volatile fluid utilized and/or modification in the size of the area of thermostatic bellows I26.

In accordance with the provisions of the pate'nt statutes. I have herein described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiments thereof, but I desire to have it understood that the apparatus disclosed is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combinations and relations described, some of these may be altered and others omitted and some of the features of each modification may be embodied in the others without interfering with the more general results outlined, and the invention extends to such use, within the scope of the appended claims.

What I claim is: I

1. The combination with a heat exchange system having a vacuum pump, of a movable control element, means for subjecting said element to fluid pressure controlled by the temperature of a fluid medium surrounding said element, means for subjecting said element to theopposing pressure of the same fluid medium which surrounds said element, and means controlled by said control element for controlling the vacuum pump to control the pressure of said fluid medium which surrounds said element.

2. The combination with a heating system having a steam generator, a supply line, a return line, and a vacuum pump for the return line, of a movable control element, means for subjecting said element to fluid pressure controlled by the temperature of a fluid medium in said return line and surrounding said element, means for subjecting said element to the opposing pressure of the same fluid medium which surrounds said element, means controlled by said control element for controlling the vacuum pump to control the pressure of said fluid medium which surrounds said element, a conduit for conveying elastic fluid supplied by said generator and discharging it into said return line, an aquastat responsive to temperature within said conduit, an adjustable choke in said conduit on the return line side of said aquastat, and means controlled by said aquastat for controlling the supply of heat to said generator.

3. The combination with a heat exchange system having a return line, of a movable control element, means for subjecting said element to fluid pressure controlled by the temperature of a fluid medium in said return line and surrounding said element, means for subjecting said element to the opposing pressure of the same fluid medium which surrounds said element, and means including an evacuating device controlled by said control element for controlling the pressure of said fluid medium which surrounds said element.

4. The combination with a heat exchange system having a return line, of a movable control element, means for subjecting said element to fluid pressure controlled by the temperature of a fluid medium in said return line and surrounding said element, means for subjecting said element to the opposing pressure of the same fluid medium which surrounds said element, and means including an evacutating device controlled by said control element for controlling the pressure and temperature of said fluid medium which surrounds said element.

5. The combination with an elastic fluid heating system having a return line and a vacuum pump, of a sealed fluid thermostat having an expansible and contractible element, means connecting said thermostat with the return line for exposing said thermostat to the pressure and temperature of the elastic fluid within the return line whereby said thermostat is subjected externally to the pressure of elastic fluid within the return line and oppositely responsive to the temperature of said elastic fluid within the return line, and means for controlling operation of the pump by said thermostat.

6. The combination with an elastic fluid heating system having a return line and a vacuum pump, of a sealed fluid thermostat having an expansible and contractible element, means connecting said thermostat with the return line for .exposing s'aid thermostat to the pressure and temperature of the elastic fluid within the return line whereby said thermostat is subjected externally to the pressure of elastic fluid within the return line and oppositely responsive to the temperature of said elastic fluid within the return line, and means including a switch for controlling operation of the pump by said thermostat.

7. A control apparatus for causing the vacuum pump of a heating system to cut out at a temperature within the return line lower by a predetermined substantially constant amount than the flash temperature of fluid within the return line, and comprising, in combination, a sealed fluid thermostat having an expansible and contractible element, means connecting said thermostat with the return line for exposing said thermostat to the pressure and temperature of the elastic fluid within the return line whereby said thermostat is oppositely responsive to tem perature and pressure of elastic fluid within the return line; pump-control means controlled by said thermostat, and adjustable means whereby said predetermined substantially constant amount may be selected.

9. The combination with a heat exchange system having liquid vaporizing meansand a return line, of a control element, means to move said control element in one direction by the temperature in the return line, means to move said control element in the opposite direction by the pressure in the return line, means including an evacuating device controlled by said control element for controlling the pressure of elastic fluid in the return line, means controlling the heat supplied to said liquid vaporizing means, and means including an aquastat controlled by the temperature of the elastic fluid inthe supply side of the system for controlling the heat controlling means.

10. The combination with a heat exchange system having liquid vaporizing means and a return line, of a control element, means to move said control element in one direction by the temperature in the return line, means to move said control element in the opposite direction by the pressure in the return line, means including an evacuating device controlled by said control element for controlling the pressure of elastic fluid in the, return line, means controlling the heat supplied to said liquid vaporizing means, and means including an adjustable aquastat controlled by the temperature of the heated elastic fluid in the supply side of the system for controlling the heat controlling means.

11. The combination with a heat exchange system having liquid vaporizing means and a return line, of a control element, means to move said control element in one direction by the temperature in the return line, means to move said control element in the opposite direction by the pressure in the return line, means including an evacuating device controlled by said control element for controlling the pressure of elastic fluid in the return line, means controlling the heat supplied to said liquid vaporizing means, and means including a thermostat responsive to atmospheric temperatures for controlling the heat controlling means.

12. The combination with a heat exchange system having liquid vaporizing means and a return line, of control means responsive to the temperature in the return line and oppositely responsive to pressure in the return line, means including an evacuating device controlled by said control means for controlling the pressure of elastic fluid in the return line, means controlling the heat supplied to said liquid vaporizing means, and means including an aquastat controlled by the temperature of the elastic fluid in the supply side of the system for controlling the said heat controlling means.

13. The combination with a heat exchange system having liquid vaporizing means and a return line, of control means responsive to the temperature in the return line and oppositely responsive to pressure in the return line, means including an evacuating device controlled by said control means for controlling the pressure of elastic fluid in the return line, means controlling the heat supplied to said liquid vaporizing means, and means including an adjustable aquastat controlled by the temperature of the elastic fluid in the supply side of the system for controlling the said heat controlling means.

14. The combination with a heat exchange system having liquid vaporizing means and a return line, of control means responsive to the temperature in the return line and oppositely responsive to pressure in the return line, means including an evacuating device controlled by said control means for controlling the pressure of elastic fluid in the return line, means controlling the heat supplied to said liquid vaporizing means, and means including a thermostat responsive to atmospheric temperatures for controlling the heat controlling means.

15. The combination with a heat exchange system having a return line, of diflerentially op-- 75 erable control means, thermal-responsive means governed by the temperature of the return line elastic fluid for controlling said differentially operable control means, pressure-responsive means governed by the pressure of the return line elastic fluid for oppositely controlling said differentially operable control means, and means including an evacuating device controlled by said differentially operable control means for controlling the pressure of the return line elastic fluid.

16. A controlling device responsive to temperatures and pressures for controlling the pressure of elastic fluids in a condensing system comprising in combination, controlling means having an expansible bellows containing volatile fluid susceptible to changes in volume and pressure for changes in temperature of the volatile fluid,

a chamber under pressure subjecting the outside of said bellows to pressure, actuating means responsive to movements of said bellows under differential pressures resulting from the pressures on the inside and outside of said bellows, switching means operable by said bellows, and another chamber containing said switching means and having but limited communication with said first named chamber so as to minimize the entry of moisture into the switch chamber.

17. A controlling device responsive to temperatures and pressures for controlling the pressure of elastic fluids in a condensing system comprising in combination, controlling means having an expansibie bellows containing volatile fluid susceptible to changes in volume and pressure for changes in temperature of the volatile fluid,

means subjecting the outside of said bellows to chamber, switch mechanism contained in said chamber for making and breaking an electrical circuit at definite points in the movement of said actuating means in response to changes in differential pressures upon said bellows and different temperatures of volatile fluid contained in said bellows, and means for minimizing the entry and the collection of moisture in the chamber containing said switch mechanism.

18. A controlling device responsive to temperatures and pressures for controlling the pressure of elastic fluids in a condensing system comprising in combination, a device having two chambers separated by a partitioning wall, an expansible bellows disposed in one of said chambers, and switching mechanism actuated by said bellows and disposed in the other of said chambers, said partitioning wall between said chambers having at least one opening therein permitting equalization of pressures in the two chambers.

19. A controlling device responsive to temperatures and pressures for controlling the pressure of elastic fluids in a condensing system comprising in combination, a device having two chambers, an expansible bellows disposed in one of said chambers, switching mechanism actuated by said bellows and disposed in the other of said chambers, means between said chambers having an opening enabling mechanical connection between said bellows and said switching mechanism whereby said switching mechanism is operated by said bellows, and means hermetically sealing said opening for preventing the flow of fluid from one of said chambers to the other, so as to prevent equalization of pressures in said chambers, but permitting transmission of motion to the switching mechanism by the mechanical connection extending through the opening.

ALFRED L. BROWNE. 

